The present invention is related to driver selected gear units for adjusting a vehicle speed and power requirements and particularly to such gear units, which are operated by servo-drives.
In vehicles equipped with servo-driven gear units, the gear shift lever is not mechanically connected with the gear unit. Instead, the gear shift lever generally operates an intermediate valve device, which is connected to the gear unit by compressed air lines, for example, to operate a power cylinder to obtain the desired gear selection. In such an arrangement, however, the operator is unable to "feel" the shifting of gears, since there is no resistance to movement of the gear shift lever. It will be understood, of course, that the operator can only engage the clutch and apply gas when the gear change has been completed. Knowledge of the gear change completion can be obtained by means of a signal light on the vehicle dashboard or by an audible signal tone, but these solutions have the disadvantage of diverting the driver's attention from his traffic-related duties.